The present invention is directed to a method of injecting a hardenable mass into cracks or capillaries of a structure. It is known to seal off cracks and capillaries in a structure, such as a concrete structure, by forcing or injecting a water-repelling hardenable mass at high pressures about 150 to 200 bar into the cracks and/or capillaries.
In DE-OS 31 17 286, a so-called packer is disclosed for the above purpose and has a tubularly-shaped filling stub which is fixed in a fluid-tight manner in a borehole formed in a structure. A rubber sleeve encircling the filling stub fixes the stub in the borehole and the sleeve is radially clamped in the borehole and undergoes an axial shortening.
In this type of attachment, a cumbersome manipulation by the user is involved. Moreover, excessive pressure and partial spalling of the surface of the structure can occur during the clamping operation in the outer region of the borehole. Furthermore, such packers have a complicated construction and, as a result, are expensive.
A simpler device as compared to the packer is disclosed in DE-OS 32 03 871. The packing device in this patent publication has essentially a conically-shaped outside configuration so that a wedge-type fastening in the borehole is achieved for the purpose of sealing using the packing device. Experience has shown that the retaining values developed are mostly insufficient for resisting the counterpressure occurring when the mass is injected, with the result that the packing device is released and the sealing action is lost.
From DE-OS 22 26 169 concerning securing anchor ties in the ground, it is known to fasten an essentially tubular-shaped anchor in the outer region of the borehole by introducing cement and water into the gap located between the anchor and the borehole wall.
After the cement mortar have set, which can require a long period of time, additional cement mortar is introduced into the deeper region of the borehole for effecting the desired anchorage.
While the present invention deals with the repair or rehabilitation of a structure such as in the method disclosed in DE-OS 22 26 169, a comparison with previously-mentioned restoration of cracked or porous structures is not possible. In this described method, the anchor tie, inserted into the borehole, passes through different layers of the ground and forms an element for holding the layers together. Accordingly, cement mortar is introduced into a gap between the anchor tie and the inside surface of the borehole for establishing a connection between the individual ground layers and the anchor tie. Since only the borehole, that is, the gap between the borehole surface and the anchor tie is to be filled with cement mortar, high pressures are not required for injecting the mortar, as would be needed in the previously-mentioned methods of repairing cracked structures. The mortar introduced into the outer region of the borehole for fixation purposes does not have to meet any higher requirements, particularly as far as compression strength is concerned. In addition, in the case of anchor ties, a long period of time is required before the completion of the anchorage, accordingly, a long setting time for the cement mortar used for filling the borehole as well as for fastening the anchor tie is acceptable.